Struts框架只允許應用中存在一個ActionServlet類,但是可以存在多個客戶化的RequestProcessor類,每個子應用模塊都可以有單獨的RequestProcessor類,
ActionServlet主要負責初始化,以及介紹請求并找到合適的RequestRrocessor,之后真正干活的是RequestProecssor和Action.
上回說到ActionServlet的process方法最終會調用RequestProcessor類的process方法.下面介紹這個方法.
一.RequestProcessor的process方法
1) 調用processMultipart()方法
如果HTTP請求方式為post,并且contentType為”multipart/form-data”開頭,標準的HttpServletRequest對象將被重新包裝,以方便處理”multipart”類型的HTTP請求.如果請求方式為get,或正congtentType屬性不是”mulitipart”,就直接返回原始的HttpServletRequest對象.
2) 調用processPath()方法
獲得請求的URI的路徑,這一信息可用于選擇合適的Struts Action組件.
3) 調用processLocale方法
當ControllerConfig對象的locale屬性為true,將讀取用戶請求中包含的Locale信息,然后把Locale實例保存在session范圍內.
4) 調用processContendType(contentType)方法
讀取ControllerConfig對象的conttentType屬性,然后調用response.setContentType(contentType)方法,設置響應結果的文檔類型和字符編碼.
processContent()方法如下
5) 調用processNoCache()方法
讀取ControllerConfig對象的nocache屬性,如果nocache屬性為true,在響應結果中將加入特定的頭參數:Pragma,Cache-Control和Expires,
防止頁面被存儲在客戶的瀏覽器的緩存中,processNoCache方法的代碼如下:
6)調用processPreprocess()方法
該方法不執行任何操作.直接返回true.子類可以覆蓋這個方法.
執行客戶化的預處理請求操作.
7)調用processMapping()方法
尋找和用戶請求的URI匹配的ActionMapping,如果不存在這樣的ActionMapping,則向用戶返回恰當的錯誤信息.
8)調用processRoles()方法
先判斷是否為Action配置了安全角色,如果配置了安全角色,就調用isUserInRole()方法判斷當前用戶是否具備必需的角色,如果不具備,就結束請求處理流程.,向用戶返回恰當的錯誤消息.
9)調用processActionForm()方法
先判斷是否為ActionMapping配置了ActionForm,如果配置了ActionForm,就先從ActionForm的存在范圍內(request或session)尋找改ActionForm實例,如果不存在,就創建一個實例,接下來把它保存在合適的范圍內,保存時使用的屬性key為ActionMapping的name屬性。
10)調用processPopulate()方法
如果為ActionMapping配置了ActionForm,就先調用ActionForm的reset()方法,再把請求中的表單數據組裝到ActionForm中。
11)調用processValidate()方法
如果為ActionMapping配置了ActionForm,并且ActionMapping的validate屬性為true,就調用ActionForm的validate()方法,如果validate方法返回的ActionErrors對象中包含ActionMessage對象,說明表單驗證失敗。就把ActionErrors對象放在request范圍內,再把請求轉發到ActionMapping的input屬性指定的Web組件。如果ActionForm的validate方法執行表單驗證成功,就繼續執行下面的處理流程。
12)調用processForward()方法
判斷是否在ActionMapping中配置了forward屬性。如果配置了這個屬性,就調用RequestDispatcher的forward方法,請求處理流程結束。否則進行下一步。
13)調用processInclude()方法
判斷是否在ActionMapping中配置了include屬性。如果配置了這個屬性,就調用RequestDispatcher的include方法,請求處理流程結束。否則進行下一步。
14)調用processActionCreate()方法
先判斷是否在Action緩存中存在這個Action實例,如果沒有就新建一個Action實例,把它放在Action緩存中。可以看出Action也是只有一個實例在運行的。
15)調用processActionPerform
該方法調用Action實例的execute方法,該方法位于try/catch中,以及捕獲異常。processActionPerform()方放代碼如下。
16)調用processActionForward方法
把你的Action的excute方法返回的ActionFoward對象作為參數傳給它,processActionForward對象包的請求轉發信息來執行請求轉發或重定向。
在RequestProcessor類的process方法中,會訪問ControllerConfig、ActionMappig和ActionForward實力的屬性,ControllerConfig類和struts配置文件的<controlle>r元素對應,ActionMapping類和<action>元素對應,ActionForward和<forward>元素對應,process方法通過訪問這三個類實例的屬性來獲得相關的配置信息。
寫了這么多,RequestProcessor干得事夠多的吧。
二.擴展RequestProcessor類
如果想修改RequestProcessor的一些默認功能,改易覆蓋RequestProcessor基類中的相關方法.
在struts配置文件中,<controller>元素的processorClass屬性用于配置你自己的RequestProcessor類
ActionServlet主要負責初始化,以及介紹請求并找到合適的RequestRrocessor,之后真正干活的是RequestProecssor和Action.
上回說到ActionServlet的process方法最終會調用RequestProcessor類的process方法.下面介紹這個方法.
一.RequestProcessor的process方法
- ? ??
- public ? void ?process(HttpServletRequest?request, ??
- ????????????????????????HttpServletResponse?response) ??
- ???????? throws ?IOException,?ServletException?{ ??
- ???????? //?Wrap?multipart?requests?with?a?special?wrapper ??
- ????????request?=?processMultipart(request); ??
- ???????? //?Identify?the?path?component?we?will?use?to?select?a?mapping ??
- ????????String?path?=?processPath(request,?response); ??
- ???????? if ?(path?==? null )?{ ??
- ???????????? return ; ??
- ????????}? ??
- ???????? if ?(log.isDebugEnabled())?{ ??
- ????????????log.debug( "Processing?a?'" ?+?request.getMethod()?+ ??
- ?????????????????????? "'?for?path?'" ?+?path?+? "'" ); ??
- ????????} ??
- ???????? //?Select?a?Locale?for?the?current?user?if?requested ??
- ????????processLocale(request,?response); ??
- ???????? //?Set?the?content?type?and?no-caching?headers?if?requested ??
- ????????processContent(request,?response); ??
- ????????processNoCache(request,?response); ??
- ???????? //?General?purpose?preprocessing?hook ??
- ???????? if ?(!processPreprocess(request,?response))?{ ??
- ???????????? return ; ??
- ????????} ??
- ???????? this .processCachedMessages(request,?response); ??
- ???????? //?Identify?the?mapping?for?this?request ??
- ????????ActionMapping?mapping?=?processMapping(request,?response,?path); ??
- ???????? if ?(mapping?==? null )?{ ??
- ???????????? return ; ??
- ????????} ??
- ???????? //?Check?for?any?role?required?to?perform?this?action ??
- ???????? if ?(!processRoles(request,?response,?mapping))?{ ??
- ???????????? return ; ??
- ????????} ??
- ???????? //?Process?any?ActionForm?bean?related?to?this?request ??
- ????????ActionForm?form?=?processActionForm(request,?response,?mapping); ??
- ????????processPopulate(request,?response,?form,?mapping); ??
- ???????? //?Validate?any?fields?of?the?ActionForm?bean,?if?applicable ??
- ???????? try ?{ ??
- ???????????? if ?(!processValidate(request,?response,?form,?mapping))?{ ??
- ???????????????? return ; ??
- ????????????} ??
- ????????}? catch ?(InvalidCancelException?e)?{ ??
- ????????????ActionForward?forward?=?processException(request,?response,?e,?form,?mapping); ??
- ????????????processForwardConfig(request,?response,?forward); ??
- ???????????? return ; ??
- ????????}? catch ?(IOException?e)?{ ??
- ???????????? throw ?e; ??
- ????????}? catch ?(ServletException?e)?{ ??
- ???????????? throw ?e; ??
- ????????} ??
- ???????????? ??
- ???????? //?Process?a?forward?or?include?specified?by?this?mapping ??
- ???????? if ?(!processForward(request,?response,?mapping))?{ ??
- ???????????? return ; ??
- ????????} ??
- ???????? if ?(!processInclude(request,?response,?mapping))?{ ??
- ???????????? return ; ??
- ????????} ??
- ???????? //?Create?or?acquire?the?Action?instance?to?process?this?request ??
- ????????Action?action?=?processActionCreate(request,?response,?mapping); ??
- ???????? if ?(action?==? null )?{ ??
- ???????????? return ; ??
- ????????} ??
- ???????? //?Call?the?Action?instance?itself ??
- ????????ActionForward?forward?= ??
- ????????????processActionPerform(request,?response, ??
- ?????????????????????????????????action,?form,?mapping); ??
- ??
- ???????? //?Process?the?returned?ActionForward?instance ??
- ????????processForwardConfig(request,?response,?forward); ??
- ??
- ????}???
public void process(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { // Wrap multipart requests with a special wrapper request = processMultipart(request); // Identify the path component we will use to select a mapping String path = processPath(request, response); if (path == null) { return; } if (log.isDebugEnabled()) { log.debug("Processing a '" + request.getMethod() + "' for path '" + path + "'"); } // Select a Locale for the current user if requested processLocale(request, response); // Set the content type and no-caching headers if requested processContent(request, response); processNoCache(request, response); // General purpose preprocessing hook if (!processPreprocess(request, response)) { return; } this.processCachedMessages(request, response); // Identify the mapping for this request ActionMapping mapping = processMapping(request, response, path); if (mapping == null) { return; } // Check for any role required to perform this action if (!processRoles(request, response, mapping)) { return; } // Process any ActionForm bean related to this request ActionForm form = processActionForm(request, response, mapping); processPopulate(request, response, form, mapping); // Validate any fields of the ActionForm bean, if applicable try { if (!processValidate(request, response, form, mapping)) { return; } } catch (InvalidCancelException e) { ActionForward forward = processException(request, response, e, form, mapping); processForwardConfig(request, response, forward); return; } catch (IOException e) { throw e; } catch (ServletException e) { throw e; } // Process a forward or include specified by this mapping if (!processForward(request, response, mapping)) { return; } if (!processInclude(request, response, mapping)) { return; } // Create or acquire the Action instance to process this request Action action = processActionCreate(request, response, mapping); if (action == null) { return; } // Call the Action instance itself ActionForward forward = processActionPerform(request, response, action, form, mapping); // Process the returned ActionForward instance processForwardConfig(request, response, forward); }
1) 調用processMultipart()方法
如果HTTP請求方式為post,并且contentType為”multipart/form-data”開頭,標準的HttpServletRequest對象將被重新包裝,以方便處理”multipart”類型的HTTP請求.如果請求方式為get,或正congtentType屬性不是”mulitipart”,就直接返回原始的HttpServletRequest對象.
2) 調用processPath()方法
獲得請求的URI的路徑,這一信息可用于選擇合適的Struts Action組件.
3) 調用processLocale方法
當ControllerConfig對象的locale屬性為true,將讀取用戶請求中包含的Locale信息,然后把Locale實例保存在session范圍內.
4) 調用processContendType(contentType)方法
讀取ControllerConfig對象的conttentType屬性,然后調用response.setContentType(contentType)方法,設置響應結果的文檔類型和字符編碼.
processContent()方法如下
- protected ? void ?processContent(HttpServletRequest?request, ??
- ?????????????????????????????????HttpServletResponse?response)?{ ??
- ??
- ???????String?contentType?=?moduleConfig.getControllerConfig().getContentType(); ??
- ??????? if ?(contentType?!=? null )?{ ??
- ???????????response.setContentType(contentType); ??
- ???????} ??
- ??
- ???}???
protected void processContent(HttpServletRequest request, HttpServletResponse response) { String contentType = moduleConfig.getControllerConfig().getContentType(); if (contentType != null) { response.setContentType(contentType); } }
5) 調用processNoCache()方法
讀取ControllerConfig對象的nocache屬性,如果nocache屬性為true,在響應結果中將加入特定的頭參數:Pragma,Cache-Control和Expires,
防止頁面被存儲在客戶的瀏覽器的緩存中,processNoCache方法的代碼如下:
- protected ? void ?processNoCache(HttpServletRequest?request, ??
- ??????????????????????????????????HttpServletResponse?response)?{ ??
- ??
- ???????? if ?(moduleConfig.getControllerConfig().getNocache())?{ ??
- ????????????response.setHeader( "Pragma" ,? "No-cache" ); ??
- ????????????response.setHeader( "Cache-Control" ,? "no-cache,no-store,max-age=0" ); ??
- ????????????response.setDateHeader( "Expires" ,? 1 ); ??
- ????????} ??
- ????}??
protected void processNoCache(HttpServletRequest request, HttpServletResponse response) { if (moduleConfig.getControllerConfig().getNocache()) { response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "no-cache,no-store,max-age=0"); response.setDateHeader("Expires", 1); } }
6)調用processPreprocess()方法
該方法不執行任何操作.直接返回true.子類可以覆蓋這個方法.
執行客戶化的預處理請求操作.
7)調用processMapping()方法
尋找和用戶請求的URI匹配的ActionMapping,如果不存在這樣的ActionMapping,則向用戶返回恰當的錯誤信息.
8)調用processRoles()方法
先判斷是否為Action配置了安全角色,如果配置了安全角色,就調用isUserInRole()方法判斷當前用戶是否具備必需的角色,如果不具備,就結束請求處理流程.,向用戶返回恰當的錯誤消息.
9)調用processActionForm()方法
先判斷是否為ActionMapping配置了ActionForm,如果配置了ActionForm,就先從ActionForm的存在范圍內(request或session)尋找改ActionForm實例,如果不存在,就創建一個實例,接下來把它保存在合適的范圍內,保存時使用的屬性key為ActionMapping的name屬性。
10)調用processPopulate()方法
如果為ActionMapping配置了ActionForm,就先調用ActionForm的reset()方法,再把請求中的表單數據組裝到ActionForm中。
11)調用processValidate()方法
如果為ActionMapping配置了ActionForm,并且ActionMapping的validate屬性為true,就調用ActionForm的validate()方法,如果validate方法返回的ActionErrors對象中包含ActionMessage對象,說明表單驗證失敗。就把ActionErrors對象放在request范圍內,再把請求轉發到ActionMapping的input屬性指定的Web組件。如果ActionForm的validate方法執行表單驗證成功,就繼續執行下面的處理流程。
12)調用processForward()方法
判斷是否在ActionMapping中配置了forward屬性。如果配置了這個屬性,就調用RequestDispatcher的forward方法,請求處理流程結束。否則進行下一步。
13)調用processInclude()方法
判斷是否在ActionMapping中配置了include屬性。如果配置了這個屬性,就調用RequestDispatcher的include方法,請求處理流程結束。否則進行下一步。
14)調用processActionCreate()方法
先判斷是否在Action緩存中存在這個Action實例,如果沒有就新建一個Action實例,把它放在Action緩存中。可以看出Action也是只有一個實例在運行的。
15)調用processActionPerform
該方法調用Action實例的execute方法,該方法位于try/catch中,以及捕獲異常。processActionPerform()方放代碼如下。
- protected ?ActionForward ??
- ???????processActionPerform(HttpServletRequest?request, ??
- ????????????????????????????HttpServletResponse?response, ??
- ????????????????????????????Action?action, ??
- ????????????????????????????ActionForm?form, ??
- ????????????????????????????ActionMapping?mapping) ??
- ??????? throws ?IOException,?ServletException?{ ??
- ??????? try ?{ ??
- ??????????? return ?(action.execute(mapping,?form,?request,?response)); ??
- ???????}? catch ?(Exception?e)?{ ??
- ??????????? return ?(processException(request,?response, ??
- ????????????????????????????????????e,?form,?mapping)); ??
- ???????} ??
- ???
protected ActionForward processActionPerform(HttpServletRequest request, HttpServletResponse response, Action action, ActionForm form, ActionMapping mapping) throws IOException, ServletException { try { return (action.execute(mapping, form, request, response)); } catch (Exception e) { return (processException(request, response, e, form, mapping)); } }
16)調用processActionForward方法
把你的Action的excute方法返回的ActionFoward對象作為參數傳給它,processActionForward對象包的請求轉發信息來執行請求轉發或重定向。
在RequestProcessor類的process方法中,會訪問ControllerConfig、ActionMappig和ActionForward實力的屬性,ControllerConfig類和struts配置文件的<controlle>r元素對應,ActionMapping類和<action>元素對應,ActionForward和<forward>元素對應,process方法通過訪問這三個類實例的屬性來獲得相關的配置信息。
寫了這么多,RequestProcessor干得事夠多的吧。
二.擴展RequestProcessor類
如果想修改RequestProcessor的一些默認功能,改易覆蓋RequestProcessor基類中的相關方法.
- Public? class ?CustomRequestProcessor? extends ?RequestProcessor{ ??
- ?? protected ? void ?processPreprocess?(HttpServletRequest?request, ??
- ?????????????????????????????????HttpServletResponse?response)?{? ??
- …………………. ??
- } ??
- }??
Public class CustomRequestProcessor extends RequestProcessor{ protected void processPreprocess (HttpServletRequest request, HttpServletResponse response) { …………………. } }
在struts配置文件中,<controller>元素的processorClass屬性用于配置你自己的RequestProcessor類
- </controller? ??
- contentType=“text/html:charset=”GB2312” ??
- locale=” true ”?nocache=” true ”?processorCalss=”com.test.CustomRequestProcessor”/>??
</controller contentType=“text/html:charset=”GB2312” locale=”true” nocache=”true” processorCalss=”com.test.CustomRequestProcessor”/>
更多文章、技術交流、商務合作、聯系博主
微信掃碼或搜索:z360901061

微信掃一掃加我為好友
QQ號聯系: 360901061
您的支持是博主寫作最大的動力,如果您喜歡我的文章,感覺我的文章對您有幫助,請用微信掃描下面二維碼支持博主2元、5元、10元、20元等您想捐的金額吧,狠狠點擊下面給點支持吧,站長非常感激您!手機微信長按不能支付解決辦法:請將微信支付二維碼保存到相冊,切換到微信,然后點擊微信右上角掃一掃功能,選擇支付二維碼完成支付。
【本文對您有幫助就好】元
